/Engine/Source/Editor/UMGEditor/Public/DesignerExtension.h
Initializes the designer extension, this is called the first time a designer extension is registered
virtual void Initialize ( [IUMGDesigner](API\Editor\UMGEditor\IUMGDesigner) * InDesigner, [UWidgetBlueprint](API\Editor\UMGEditor\UWidgetBlueprint) * InBlueprint )